Mass Spectrometer. This instrument will be part of an analytical facility for the characterization of biopolymers including peptides\Proteins, nucleicacids and oligosaccharides. Other instruments already available for the characterization of proteins are two gas phase protein sequencers ABI models 470A and 477A with 120A PTH analyzers; an HPLC based, OPA post column derivatization, fully computerized amino acid analyzer (detection limit Ca 10 pM). The major user group consists of seven investigators with NIH sponsored research Interests. Proposals focus on the structural characterization of synthetic peptides, proteins and nucleotides as well as, most importantly, of isolated peptides and proteins from natural sources. The principal justification for the requested instrument is the need to establish a state of the art capability in protein characterization, complementing our strong and classic Edman degradation approach. Most peptides and proteins of interest are postranslationally modified and may be glycosylated, sulfated, or phosphorylated or contain such amino acids or carboxyglutamic acid, hydroxyproline or hydroxylysine, among others. Instrument capabilities should include the ability to analyze high masses and be extremely sensitive as the proteins of interest are available in very limited quantities. Use of the instrument to identify certain proteins as they are being purified is contemplated. An advisory committee will be responsible for the overall guidance of the shared instrumentation program, for setting scientific priorities in general terms and for resolution of possible scheduling conflicts. It is anticipated that up to 30% of the instrument time will be made available for samples originating from those different investigators outside the Clayton Foundation Laboratories for Peptide Biology. The Salk Institute has committed in excess of $300,000 toward the purchase to the instrument, manning of the instrument and renovation of space. Long-range maintenance and upkeep responsibilities will be funded on a recharge basis with Salk Institute's subsidies if necessary.